Earlier this month, a grand jury began hearing from staff members working for state House Democratic leaders regarding a huge spike in year-end bonuses that made news early this year. The $1.9 million in year-end bonuses paid by House Democratic leaders in late 2006, which was a pivotal election year, were four times larger than the bonuses paid in 2005, a non-election year.

Last week, House Democratic leaders filed appeals with the state Supreme Court to block any more staffers from testifying before the grand jury.

State Attorney General Tom Corbett has been investigating the bonuses because it is illegal to use tax dollars to pay for campaign work, and press reports have suggested that's exactly what happened.

An investigation by a Pittsburgh newspaper revealed that 80 of the top 100 bonus awards went to people who had worked on or contributed to the campaigns of former Rep. Mike Veon, House Majority Leader H. William DeWeese or the caucus campaign committee.

As part of Corbett's investigation, agents from the attorney general's office removed documents from the House Democrats' Office of Legislative Research. The newspaper probe found that eight employees from that office left their government jobs for several months to work on political campaigns of House Democrats — and, coincidentally, were given year-end bonuses ranging from $5,000 to $15,065.

No House Democratic officials involved in the bonus scandal are willing to talk about the legal action being taken to prevent further testimony before the grand jury.

The evidence clearly suggests that campaign work was paid for with taxpayer dollars, but the investigation must go forward to get all of the facts and testimony from those involved. The huge spike in year-end bonuses coincided with extraordinary campaign efforts that resulted in Democrats regaining the majority status in the House, which they had lost 10 years earlier.

While the evidence revealed by journalists' investigations already suggests that campaign-related work was paid for with taxpayer dollars, the Democrats' latest move to block the subpoenas only makes it look more like House Democrats are trying to hide something.

The practice of using tax dollars to reward campaign workers might well have been common and practiced to some degree by both parties in the past. But the dramatic increase in bonuses, to nearly $2 million in a critical campaign year, certainly warrants an investigation. And it's reasonable to think that such an investigation would cause lawmakers to think twice about such arrangements in the future.

Trying to block this investigation only darkens the cloud building over Democrat leadership in the House.